The present invention relates to floor cleaning machines and in particular to automatic floor cleaning and treating machines which are used for the cleaning of hard surfaces of large floor areas, such as e.g. in hotels, factories, office buildings, shopping centers and the like.
In general such machines comprise a movable body supported by a pair of drive wheels and one or more caster wheels, the body carrying a brushing means, reservoirs for storing fresh and spent cleaning liquid, means for dosing fresh cleaning liquid onto the floor and a squeegee/vacuum pickup system for recovering spent cleaning liquid from the floor.
The brushing means normally comprises one or more rotatable brushes, a motor for driving the brushes and a means for lifting the brushes off the floor when large areas are traversed without any cleaning action being required.
A number of conventional floor cleaning machines also include an option for adjustment of the brush height with respect to the floor. In general adjustment of the brush height has to be done manually which severely limits the easy controllability during operation.
In view of uniform cleaning, wear of the brushes and energy consumption, it is often more advantageous to control not so much the brush heigth, but the brush pressure. In U.S. Pat. No. 4,218,798 a control system has been disclosed whereby the brush pressure is operator-adjustable. Brush pressure control is achieved by means of a hydraulic/pneumatic actuator system whereby the pressure level is adjustable by way of a pressure regulator.